1. Field of the Invention
The invention relates to radiation-curable compounds, to processes for preparing them, to their use, and to coating materials comprising them.
2. Background of the Invention
EP-A 902 040 describes radiation-curable urethane acrylates based on aliphatic isocyanurates and biurets.
EP-A 903 363 describes radiation-curable urethane acrylates based on isocyanurates or biurets, if appropriate in a mixture, and on a monomeric cycloaliphatic isocyanate. Hydroxy-functional compounds disclosed are merely general lists of ethylenically unsaturated compounds having at least one reactive OH group and, optionally, different compounds comprising OH groups.
A disadvantage of the two last-mentioned disclosures is that the coating materials comprising such polyurethane acrylates form coatings which though hard and scratch-resistant are brittle.
The German patent application DE 10346327 A1 discloses radiation-curable urethane acrylates based on isocyanurates or biurets, if appropriate in a mixture, and on ethylenically unsaturated hydroxy compounds in merely general lists, and also polytetrahydrofuran as dihydroxy compounds.
A disadvantage of that document is that the coating materials comprising such polyurethane acrylates lead to coatings which though flexible lack scratch resistance.
It was an object of the present invention to provide further radiation-curable compounds which are to be curable by means of electromagnetic radiation, preferably UV radiation and in particular UV-A radiation. The coating materials obtained ought to exhibit low viscosity, high hardness and scratch resistances in conjunction with good flexibility, and a high reactivity on irradiation.